This invention relates generally to aquacycles, and more particularly to apparatus for conversion of a bicycle into a buoyant, maneuverable, pedal-operable aquacycle.
Pedal operated flotation devices are well-known They provide, for one or more riders, a buoyant hull assembly, pedal operated propulsion means, e.g. a paddle wheel or a propeller, and steering control, e.g. a rudder. Most are intended for recreational purposes, and provide minimal, and frequently inefficient, propulsion. Typically, such recreational water craft are offered for rental only, and then only in a resort setting.
Amphibious craft which are pedal operable on land and water are not unheard of, but require much time and effort to convert, and compromise their efficient operation on land, water or both. Bulky hardware and tools burden the operator of such amphibious craft, and become undesirable ballast for both the rider of the bike and the driver of the boat. Depending upon the design of the conversion kit, the efficiency with which one operates the bicycle on land, or the boat in water, may be impaired. For example, frame supporting members that connect the bicycle to the hull assembly may require the removal of a fender, a kickstand, or other accessories. Conversely, if left installed, such bicycle accessories may interfere with operation of the water craft. Often, adaptive structures themselves cause damage to the bicycle, e.g. bent spokes result, by use of the front wheel of the bicycle to control the rudder of the boat, from wedging a rudder control arm therebetween.
The design of aquacycle conversion kits frequently ignores the limitations of the bicycle and its rider, or ignores the requirements of the aquacycle and its driver. A propeller meets more frictional resistance when turning in water than does a wheel when rolling on pavement Thus, the torque required to propel a water craft is greater than that required to propel a bicycle. When the full weight of the driver of the aquacycle is borne by a propeller driving friction wheel, the aquacycle becomes difficult to operate. When the friction wheel is disposed beneath the rear wheel of the bicycle to rotate in the plane thereof, the 90.degree. angle through which the rotation must be translated to propel the water craft forward is thought to require a heavy, complex and costly gear train Frequently, the propeller is offset by the gear train from the center line of the aquacycle, resulting in asymmetric forward thrust Finally, rudder control systems associated with the front wheel of the bicycle sometimes produce steering of the water craft in a direction opposite the turning of the handlebars, a most unnatural and undesirable result.
One such water cycle conversion device is disclosed in U.S. Pat. No. 4,493,657. In addition to suffering most of the drawbacks described above, the device described therein supports a bicycle by a base framework including a square pipe joined near the pedal hub to one of the inclined lower frame members. While relatively simple, this support arrangement places significant stress on both the bicycle frame and the hull assembly to which the square pipe is secured. In the operation of an aquacycle, significant lateral forces tend to urge a bicycle and its rider toward the left and toward the right as the pedals are operated By securing the frame of the bicycle well below its center of gravity, the device is inefficient in overcoming the normal torsional forces incident upon the hull assembly and its bicycle support frame work, causing undue stress and the risk of premature failure.
For the serious amphibious craft enthusiast, durability, maneuverability and convertibility of the aquacycle are musts. A means of vertically stabilizing and supporting the bicycle above the hull assembly must be provided that, while resisting lateral movement of the bicycle and its rider, does not unduly stress or damage the bicycle or the hull assembly. Adequate propulsion must be produced in response to effort expended by the driver of the aquacycle. When the driver turns the handlebars to the right, the aquacycle should turn port (right); when the driver turns the handlebars to the left, the aquacycle should turn starboard (left). Finally, when an afternoon of aquatic work or pleasure is over, conversion of the aquacycle back into a bicycle should not take longer than the ride home.
Accordingly, it is an object of this invention to provide aquacycle conversion apparatus that transforms a bicycle into a maneuverable, pedal-operable aquacycle.
Another object is to provide apparatus that enables the quick and easy transformation of a bicycle to an aquacycle and vice versa.
A further object is to provide an aquacycle that provides ample, even, forward thrust.
Yet another object of the invention is to provide an aquacycle, the steering of which feels natural to the rider of a bicycle.
According to the preferred embodiment of the invention, aquacycle conversion apparatus includes a twin hull assembly, and a bicycle support framework mounted thereon and capable of supporting and vertically stabilizing a bicycle by the bicycle's horizontal high frame member, i.e. a frame member located well above the bicycle's center of gravity. A forward frame member extending between the laterally spaced floats of the twin hull assembly includes a rudder control arm pivotally mounted thereon The arm has opposite ends radiating from the mount, and a transversely mounted concave wheel well extending upwardly therefrom. The wheel well is dimensioned to receive the lower portion of the front wheel of the bicycle such that pivotal movement of the front wheel of the bicycle, when received in the well, results in one-to-one pivotal movement of the arm.
A rear frame member, similarly disposed between twin hulls, provides structural support for a twin screw propulsion system and the remainder of the rudder control system The propulsion system includes a friction wheel that rotates with the rear wheel of the bicycle by pedal action and that rotates, in turn, dual flexible axles that drive oppositely threaded and pitched, laterally spaced propellers. The propellers rotate in bearings mounted below, and rearwardly of the rear frame member, and provide, in operation, substantial, symmetrical forward thrust.
Behind each propeller is a rudder, pivotable upon a generally vertical shaft that rotates within a bearing assembly also mounted to the rear frame member. A pulley, mounted atop each shaft, is pivoted, under control of the rudder control arm, via a cable extending between opposite ends thereof, and around and operatively engaging the two pulleys. The cable is routed through the two pulleys in a manner enabling same-direction pivoting of the two rudders in a direction opposite to that of the front wheel, which is turned, conventionally, by the handlebars.
By supporting the bicycle above and between the twin hulls, the support framework prevents the entire weight of the bicycle and its rider from bearing on either the front wheel well part of the rudder control arm or the friction wheel part of the propulsion system This novel feature makes it possible for the driver of the aquacycle to pedal operate the propellers without undue strain, even when the bicycle is in high gear. By the placement of the dual rudders in line with the twin propellers, turning efficiency is increased. The conversion apparatus is made primarily of polyvinyl chloride (PVC) tubing and fittings, and conversion from bicycle to aquacycle requires U-bolts, a tightening tool, and a few moment's time.
These and other advantages and features of the invention will become more fully apparent when the detailed description below is read with reference to the accompanying drawings.